1. Field of the Invention
This invention relates to a system, software, and method for quantitatively measuring lung tissue damage, esp. regional or lobe damage, by measuring the mineral density deviations and/or mineral composition deviations from normal in a CT scan combined with measurements of airflow lung function measurements. This can be used in measuring lung exposure, damage, disease risk, and response to therapy using radiological techniques in combination with data analysis. The methods described here can also be applied to other diseases that involve mineralization including COPD, esophageal cancer, cardiovascular diseases, and osteoarthritis.
2. Background of the Invention
According to the National Cancer Institute, the number of new cases of lung cancer in 2007 (both non-small cell and small cell combined) is estimated to be 213,380, and the number of deaths is estimated to be 160,390. There currently is no reliable method for measuring an individual's lung damage and risk for developing lung cancer. Lung cancer screening trials rely on age and individual reported exposure to cigarette smoke and other carcinogens to identify a high risk screening population. This method of lung cancer risk assessment provides a crude estimate of carcinogenic exposure and does not take into account (a) the damage the specific individual has sustained as a result of a wide range of potential lung tissue insults and (b) the variation in individual response to the exposure. An objective method for measuring the amount of lung tissue damage an individual has sustained would be of great benefit to effectively monitor and manage lung cancer risk groups and personalize disease monitoring and treatment of lung cancer patients.
Computed tomography scanning technology has improved dramatically in the last 10 years. Most health care institutions in the United States are now able to routinely obtain thin slice CT scans of the entire lung within a few seconds. The detailed x-ray attenuation measurements these scans produce have the potential to reveal important information relating to the progression and management of lung cancer, chronic obstructive pulmonary disease (COPD), and other smoking related diseases. Numerous studies have revealed important CT imaging features that provide important clinical information that is now important to the early management of thoracic diseases. Thin slice CT allowed for the differentiation of part-solid lung lesions, which must be managed more aggressively due to their high probability of malignancy when detected at baseline. In addition, high resolution CT measurements of airway wall thickness and the extent of emphysema is providing new insight into the management of COPD.
The fields of environmental health and aerosol sciences have also studied the fundamental mechanisms leading to lung cancer. These studies have found that the deposition of particulate matter in the lung, as occurs when smoking, has particular patterns of distribution. Of particular importance is the analysis of air flow patterns in human airways. Several studies have shown that certain structures in the airways, particularly the carinal ridge at airway bifurcations, receive significantly more particulate deposition than other locations in the lung. Smoking population studies have further revealed that for some exposures airway branching levels above three or four receive significantly more particulate load than other airway regions. It is these high exposure locations that both receive a disproportionate amount of particulate load and have the potential to provide an early indication of the level of damage sustained throughout the rest of the lung.
It is further well known that airways contain large amounts of hyaline cartilage which has the property that it mineralizes, i.e. calcifies, with various forms of repeated stress and age.